1. |
Dakshinamurthy M.^{♦}, Kowalczyk-Gajewska K., Vadillo G.^{♦}, Influence of crystallographic orientation on the void growth at the grain boundaries in bi-crystals,
INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES, ISSN: 0020-7683, DOI: 10.1016/j.ijsolstr.2020.11.035, Vol.212, pp.61-79, 2021Streszczenie: Void growth and morphology evolution in fcc bi-crystals are investigated using crystal plasticity finite element method. For that purpose, representative volume element of bi-crystals with a void at the grain boundary are considered in the analysis. Grain boundary is assumed initially perpendicular/coaxial with the straight sides of the cell. Fully periodic boundary conditions are prescribed in the representative volume element and macroscopic stress triaxiality and Lode parameter are kept constant during the whole deformation process. Three different pairs of crystal orientations characterized as hard-hard, soft-soft and soft-hard have been employed for modelling the mechanical response of the bi-crystal. Simulations are performed to study the implications of triaxiality, Lode parameter and crystallographic orientation on slip mechanism, hardening and hence void evolution. The impact of void presence and its growth on the heterogeneity of lattice rotation and resulting grain fragmentation in neighbouring areas is also analysed and discussed. Słowa kluczowe: crystal plasticity, bi-crystals, void growth, stress triaxiality, Lode parameter, unit cell calculations Afiliacje autorów:
Dakshinamurthy M. | - | University Carlos III of Madrid (ES) | Kowalczyk-Gajewska K. | - | IPPT PAN | Vadillo G. | - | University Carlos III of Madrid (ES) |
| | 140p. |
2. |
Frydrych K., Libura T., Kowalewski Z., Maj M., Kowalczyk-Gajewska K., On the role of slip, twinning and detwinning in magnesium alloy AZ31B sheet,
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING, ISSN: 0921-5093, DOI: 10.1016/j.msea.2021.141152, Vol.813, pp.141151-1-14, 2021Streszczenie: The paper reports experimental and numerical study of different deformation mechanisms activated in the AZ31B mag nesium alloy sheet subjected to cyclic in-plane tensile – compressive deformation. The influence ofslip, twinning and detwinning upon the mechanical response and texture evolution of the material is thoroughly investigated. The regime of twinning and detwinning activity is assessed based on the variation of hardening modulus in the course of the process. Velocity-based large strain crystal plasticity model accounting for twinning and detwinning is formulated. The crystal plasticity model parameters are identified using the implementation of the evolutionary algorithm. Predicted activity of deformation mechanisms is discussed with respect to the experimental data. Słowa kluczowe: twinning, detwinning, crystal plasticity, magnesium alloys, AZ31B, evolutionary algorithm Afiliacje autorów:
Frydrych K. | - | IPPT PAN | Libura T. | - | IPPT PAN | Kowalewski Z. | - | IPPT PAN | Maj M. | - | IPPT PAN | Kowalczyk-Gajewska K. | - | IPPT PAN |
| | 140p. |
3. |
Girard G.^{♦}, Frydrych K., Kowalczyk-Gajewska K., Martiny M.^{♦}, Mercier S.^{♦}, Cyclic response of electrodeposited copper films. Experiments and elastic-viscoplastic mean-field modeling,
Mechanics of Materials, ISSN: 0167-6636, DOI: 10.1016/j.mechmat.2020.103685, Vol.153, pp.103685-1-103685-17, 2021Streszczenie: The goal of the present work is to identify and model the elastic-viscoplastic behavior of electrodeposited copper films under tension-compression loadings. From the experimental point of view, as proposed in the literature, a film of copper is electrodeposited on both sides of an elastic compliant substrate. The overall specimen is next subjected to tensile loading-unloadings. As the substrate remains elastic, the elastic–plastic response of copper under cyclic loading is experimentally determined. A clear kinematic hardening behavior is captured. To model the mechanical response, a new elastic-viscoplastic self-consistent scheme for polycrystalline materials is proposed. The core of the model is the tangent additive interaction law proposed in Molinari (2002). The behavior of the single grain is rate dependent where kinematic hardening is accounted for in the model at the level of the slip system. The model parameters are optimized via an evolutionary algorithm by comparing the predictions to the experimental cyclic response. As a result, the overall response is predicted. In addition, the heterogeneity in plastic strain activity is estimated by the model during cyclic loading. Słowa kluczowe: electrodeposited copper, self-consistent scheme, elasto-viscoplasticity, kinematic hardening, experiments Afiliacje autorów:
Girard G. | - | Lorraine University (FR) | Frydrych K. | - | IPPT PAN | Kowalczyk-Gajewska K. | - | IPPT PAN | Martiny M. | - | Lorraine University (FR) | Mercier S. | - | Clermont Université (FR) |
| | 100p. |
4. |
Majewski M., Hołobut P., Kursa M., Kowalczyk-Gajewska K., Packing and size effects in elastic-plastic particulate composites: micromechanical modelling and numerical verification,
International Journal of Engineering Science, ISSN: 0020-7225, DOI: 10.1016/j.ijengsci.2020.103271, Vol.151, pp.103271-1-18, 2020Streszczenie: The issue of applicability of the Morphologically Representative Pattern (MRP) approach to elastic-plastic composites is addressed. The extension to the regime of non-linear material behaviour is performed by employing the concept of incremental linearization of the material response in two basic variants: tangent and secant. The obtained predictions are evaluated through comparison with the outcomes of numerical analyses. Finite Element simulations are carried out using periodic unit cells with cubic arrangements of spherical particles and representative volume elements (RVE) with 50 randomly placed inclusions. In addition to the analysis of the packing effect in two-phase composites, the size effect is also studied by assuming an interphase between the matrix and inclusions. It is concluded that the MRP approach can be used as an effective predictive alternative to computational homogenization, not only in the case of linear elasticity but also in the case of elastic-plastic composites. Słowa kluczowe: particulate composites, elastoplasticity, micromechanics, size effect, packing effect, morphologically representative pattern Afiliacje autorów:
Majewski M. | - | IPPT PAN | Hołobut P. | - | IPPT PAN | Kursa M. | - | IPPT PAN | Kowalczyk-Gajewska K. | - | IPPT PAN |
| | 200p. |
5. |
Kowalczyk-Gajewska K., Maździarz M., Elastic properties of nanocrystalline materials of hexagonal symmetry: the core-shell model and atomistic estimates,
International Journal of Engineering Science, ISSN: 0020-7225, DOI: 10.1016/j.ijengsci.2020.103393, Vol.157, pp.103393-1-21, 2020Streszczenie: Anisotropic core-shell model of a nano-grained polycrystal is extended to estimate the effective elastic stiffness of several metals of hexagonal crystal lattice symmetry. In the approach the bulk nanocrystalline material is described as a two-phase medium with different properties for a grain boundary zone and a grain core. While the grain core is anisotropic, the boundary zone is isotropic and has a thickness defined by the cutoff radius of a corresponding atomistic potential for the considered metal. The predictions of the proposed mean-field model are verified with respect to simulations performed with the use of the Large-scale Atomic/Molecular Massively Parallel Simulator, the Embedded Atom Model, and the molecular statics method. The effect of the grain size on the overall elastic moduli of nanocrystalline material with random distribution of orientations is analyzed. Słowa kluczowe: molecular statics, elasticity, polycrystal, effective medium, hexagonal symmetry Afiliacje autorów:
Kowalczyk-Gajewska K. | - | IPPT PAN | Maździarz M. | - | IPPT PAN |
| | 200p. |
6. |
Frydrych K., Maj M., Urbański L., Kowalczyk-Gajewska K., Twinning-induced anisotropy of mechanical response of AZ31B extruded rods,
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING, ISSN: 0921-5093, DOI: 10.1016/j.msea.2019.138610, Vol.771, pp.138610-1-14, 2020Streszczenie: Texture and twinning-induced anisotropy of the yield stress and hardening of AZ31B extruded rods is investigated. The multidirectional compression tests involving strain path changes are performed in order to: i. assess which slip and twinning systems are active in the polycrystalline sample with a strong texture, ii. analyze the influence of the preliminary deformation upon twin formation, iii. observe the resulting change of the mechanical response. In order to fulfil these goals mechanical testing is supplemented by microstructure analysis. Experimental observations are used to validate the proposed crystal plasticity framework when it is combined with the viscoplastic self-consistent scheme. On the other hand, the results of numerical simulations are used to confirm an advocated interpretation of experimental findings. Finally, the experimental and numerical results are discussed with respect to the theoretical study of slip and twinning activity on the basis of the generalized Schmid criterion. It is concluded that twinning activity influences the mechanical response predominantly by the texture change and to lesser extent by modification of strain hardening due to slip-twin interactions. Słowa kluczowe: crystal plasticity, anisotropy, plastic deformation, twinning, hcp Afiliacje autorów:
Frydrych K. | - | IPPT PAN | Maj M. | - | IPPT PAN | Urbański L. | - | IPPT PAN | Kowalczyk-Gajewska K. | - | IPPT PAN |
| | 140p. |
7. |
Rutecka A.^{♦}, Kursa M., Pietrzak K.^{♦}, Kowalczyk-Gajewska K., Makowska K.^{♦}, Wyszkowski M., Damage evolution in AA2124/SiC metal matrix composites under tension with consecutive unloadings,
ARCHIVES OF CIVIL AND MECHANICAL ENGINEERING, ISSN: 1644-9665, DOI: 10.1007/s43452-020-00134-x, Vol.20, No.4, pp.135-1-18, 2020Streszczenie: Nonlinear properties of metal matrix composites (MMCs) are studied. The research combines results of loading-unloading tensile tests, microstructural observations and numerical predictions by means of micromechanical mean-field models. AA2124/SiC metal matrix composites with SiC particles, produced by the Aerospace Metal Composites Ltd. (AMC) are investigated. The aluminum matrix is reinforced with 17% and 25% of SiC particles. The best conditions to evaluate the current elastic stiffness modulus have been assessed. Tensile tests were carried out with consecutive unloading loops to obtain actual tensile modulus and study degradation of elastic properties of the composites. The microstructure examination by scanning electron microscopy (SEM) showed a variety of phenomena occurring during composite deformation and possible sources of elastic stiffness reduction and damage evolution have been indicated. Two micromechanical approaches, the incremental Mori–Tanaka (MT) and self-consistent (SC) schemes, are applied to estimate effective properties of the composites. The standard formulations are extended to take into account elasto-plasticity and damage development in the metal phase. The method of direct linearization performed for the tangent or secant stiffness moduli is formulated. Predictions of both approaches are compared with experimental results of tensile tests in the elastic–plastic regime. The question is addressed how to perform the micromechanical modelling if the actual stress–strain curve of metal matrix is unknown. Słowa kluczowe: metal matrix composites, tension with unloadings, damage, microstructure, non-linear effective properties Afiliacje autorów:
Rutecka A. | - | inna afiliacja | Kursa M. | - | IPPT PAN | Pietrzak K. | - | inna afiliacja | Kowalczyk-Gajewska K. | - | IPPT PAN | Makowska K. | - | Motor Transport Institute (PL) | Wyszkowski M. | - | IPPT PAN |
| | 140p. |
8. |
Kowalczyk-Gajewska K., Pieczyska E.A., Golasiński K.M., Maj M., Kuramoto S.^{♦}, Furuta T.^{♦}, A finite strain elastic-viscoplastic model of gum metal,
International Journal of Plasticity, ISSN: 0749-6419, DOI: 10.1016/j.ijplas.2019.02.017, Vol.119, pp.85-101, 2019Streszczenie: A hyperelastic-viscoplastic model of Gum Metal is presented. The model is formulated in the large strain framework. The free energy function is postulated consisting of the hyperelastic and viscoplastic components. Original extension of the Neo-Hooke model with a power law component is proposed for hyperelasticity, which enables to describe a relatively large non-linear elastic regime observed for the alloy. Viscoplastic strain follows the Perzyna-type law with an overstress function. The model is implemented into the finite element method and used to simulate the Gum Metal response in multiple tension loading-unloading cycles. The results are compared with experimental outcomes. Good accordance of the simulation results and the available experimental data is obtained. Słowa kluczowe: large strain, hyperelasto-viscoplasticity, gum metal, cyclic deformation Afiliacje autorów:
Kowalczyk-Gajewska K. | - | IPPT PAN | Pieczyska E.A. | - | IPPT PAN | Golasiński K.M. | - | IPPT PAN | Maj M. | - | IPPT PAN | Kuramoto S. | - | Ibaraki University Japan (JP) | Furuta T. | - | Toyota Central Research & Development Laboratories (JP) |
| | 200p. |
9. |
Mercier S.^{♦}, Kowalczyk-Gajewska K., Czarnota C.^{♦}, Effective behavior of composites with combined kinematic and isotropic hardening based on additive tangent Mori–Tanaka scheme,
COMPOSITES PART B-ENGINEERING, ISSN: 1359-8368, DOI: 10.1016/j.compositesb.2019.107052, Vol.174, pp.107052-1-21, 2019Streszczenie: The goal of the present work is to propose a multi-scale approach for composite materials which accounts for kinematic hardening in the phases. For that purpose, the additive/sequential interaction rule and tangent linearization of viscoplastic response proposed for elastic–viscoplastic material can be extended in a straightforward manner. A two phase composite where each phase is elastic–viscoplastic is considered. The viscoplastic flow is governed by a J2 flow theory with an overstress. To find the overall behavior of the composite, a Mori–Tanaka model is applied. Numerical validation of the proposition is carried out by considering a representative volume element with 30 inclusions. Various configurations have been tested: hard or soft inclusion cases with or without isotropic hardening. It is shown that the quality of the model predictions is not affected by the introduction of the kinematic hardening component in the local constitutive behavior. Namely, in most cases considered in the paper the overall stress–strain response as well as the average stress–strain response per phase is accurately estimated. It has been also verified that the obtained backstress components are consistent with the ones predicted by Finite element calculations with ABAQUS Software. Słowa kluczowe: elastic-viscoplasticity, homogenization, finite element, metal matrix composite, Mori–Tanaka scheme, kinematic hardening Afiliacje autorów:
Mercier S. | - | Clermont Université (FR) | Kowalczyk-Gajewska K. | - | IPPT PAN | Czarnota C. | - | CNRS (FR) |
| | 200p. |
10. |
Kowalczyk-Gajewska K., Maździarz M., Effective stiffness tensor of nanocrystalline materials of cubic symmetry: the core-shell model and atomistic estimates,
International Journal of Engineering Science, ISSN: 0020-7225, DOI: 10.1016/j.ijengsci.2019.103134, Vol.144, pp.103134-1-24, 2019Streszczenie: Anisotropic core-shell model of a nano-grained polycrystal, proposed recently for nanocrystalline copper, is applied to estimate elastic effective properties for a set of crystals of cubic symmetry. Materials selected for analysis differ in the lattice geometry (face-centered cubic vs. body-centered cubic) as well as the value of a Zener factor: a ratio of two shear moduli defining elastic anisotropy of a cubic crystal. The predictions are verified by means of the atomistic simulations. The dependence of the overall bulk and shear moduli on the average grain diameter is analysed. In the mean-field approach the thickness of the shell is specified by the cutoff radius of a corresponding atomistic potential, while the grain shell is isotropic and its properties are identified by molecular simulations performed for very small grains with approximately all atoms belonging to the grain boundary zone. It is shown that the core-shell model provides predictions of satisfactory qualitative and quantitative agreement with atomistic simulations. Performed study indicates that the variation of the bulk and shear moduli with the grain size changes qualitatively when the Zener anisotropy factor is smaller or greater than one. Słowa kluczowe: molecular statics, elasticity, polycrystal, effective medium, cubic symmetry Afiliacje autorów:
Kowalczyk-Gajewska K. | - | IPPT PAN | Maździarz M. | - | IPPT PAN |
| | 200p. |
11. |
Frydrych K., Kowalczyk-Gajewska K., Prakash A.^{♦}, On solution mapping and remeshing in crystal plasticity finite element simulations: application to equal channel angular pressing,
MODELLING AND SIMULATION IN MATERIALS SCIENCE AND ENGINEERING, ISSN: 0965-0393, DOI: 10.1088/1361-651X/ab28e3, Vol.27, No.7, pp.075001-1-27, 2019Streszczenie: Microstructure evolution in crystalline materials subjected to different loading conditions is regularly studied using crystal plasticity finite element simulations. Accurate and reliable description of the microstructure, particularly in the case of large deformations, requires the usage of remeshing procedures and the mapping of the material state from the distorted mesh onto a new mesh. In this work, we evaluate three different solution mapping schemes, viz. closest point projection (CPP), sequential spherical linear interpolation (SLERP), and weighted spherical averages, all of which are based on the mapping of crystal plasticity variables. The results show that the mapping with CPP is generally acceptable, whilst the sequential SLERP is a more robust method with little additional computing effort. Słowa kluczowe: crystal plasticity, solution mapping, remeshing, severe plastic deformation SPD, equal channel angular pressing ECAP Afiliacje autorów:
Frydrych K. | - | IPPT PAN | Kowalczyk-Gajewska K. | - | IPPT PAN | Prakash A. | - | Institute of Mechanics and Fluid Dynamics (DE) |
| | 70p. |
12. |
Kursa M., Kowalczyk-Gajewska K., Lewandowski M.J., Petryk H., Elastic-plastic properties of metal matrix composites: Validation of mean-field approaches,
EUROPEAN JOURNAL OF MECHANICS A-SOLIDS, ISSN: 0997-7538, DOI: 10.1016/j.euromechsol.2017.11.001, Vol.68, pp.53-66, 2018Streszczenie: Several micromechanical and numerical approaches to estimating the effective properties of heterogeneous media are analyzed. First, micromechanical mean-field estimates of elastic moduli for selected metal matrix composite systems are compared with the results of finite element calculations performed for two simplified unit cells: spherical and cylindrical. Advantages and deficiencies of such numerical verification of analytical homogenization schemes are indicated. Next, predictions of both approaches are compared with available experimental data for two composite systems for tension and compression tests in the elastic-plastic regime using tangent and secant linearization procedures. In the examined range of strain and ceramic volume content, both the Mori-Tanaka averaging scheme and the generalized self-consistent scheme lead to reliable predictions when combined with the tangent linearization, while the use of secant moduli results in a too stiff response. It is also found that the mean-field predictions for a small ceramic volume content are very close to the results obtained from the finite-element analysis of a spherical unit cell. Słowa kluczowe: Metal-matrix composites, Effective properties, Analytical estimates, Numerical homogenization, Nonlinear analysis Afiliacje autorów:
Kursa M. | - | IPPT PAN | Kowalczyk-Gajewska K. | - | IPPT PAN | Lewandowski M.J. | - | IPPT PAN | Petryk H. | - | IPPT PAN |
| | 40p. |
13. |
Kowalczyk-Gajewska K., Maździarz M., Atomistic and mean-field estimates of effective stiffness tensor of nanocrystalline copper,
International Journal of Engineering Science, ISSN: 0020-7225, DOI: 10.1016/j.ijengsci.2018.04.004, Vol.129, pp.47-62, 2018Streszczenie: The full elasticity tensor for nano-crystalline copper is derived in molecular simulations by performing numerical tests for a set of generated samples of the polycrystalline material. The results are analysed with respect to the anisotropy degree of the overall stiffness tensor resulting from the limited number of grain orientations and their spatial distribution. The dependence of the overall bulk and shear moduli of an isotropized polycrystal on the average grain diameter is analysed. It is found that while the shear modulus decreases with grain size, the bulk modulus shows negligible dependence on the grain diameter and is close to the bulk modulus of a single crystal. A closed-form mean-field model of effective elastic properties for a bulk nano-grained polycrystal with cubic grains, i.e. made of a material with cubic symmetry, is formulated. In the model all parameters are based on the data for a single crystal and on the averaged grain size without any need for additional fitting. It is shown that the proposed model provides predictions of satisfactory qualitative and quantitative agreement with atomistic simulations. Słowa kluczowe: Molecular statics, Elasticity, Polycrystal, Effective medium, Nano-crystalline copper Afiliacje autorów:
Kowalczyk-Gajewska K. | - | IPPT PAN | Maździarz M. | - | IPPT PAN |
| | 40p. |
14. |
Frydrych K., Kowalczyk-Gajewska K., Microstructure Evolution in Cold-Rolled Pure Titanium: Modeling by the Three-Scale Crystal Plasticity Approach Accounting for Twinning,
METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE, ISSN: 1073-5623, DOI: 10.1007/s11661-018-4676-2, Vol.49, No.8, pp.3610-3623, 2018Streszczenie: A three-scale crystal plasticity model is applied to simulate microstructure evolution in hcp titanium subjected to cold rolling. Crystallographic texture and misorientation angle development, as an indicator of grain refinement, are studied. The impact of twinning activity on both phenomena is accounted for by combining the original three-scale formulation with the probabilistic twin-volume consistent (PTVC) reorientation scheme. The modeling results are compared with available experimental data. It is shown that the simulated textures are in accordance with the experimental measurements. The basic components of misorientation angle distribution, especially in the range of high angle boundaries, are also well reproduced. Afiliacje autorów:
Frydrych K. | - | IPPT PAN | Kowalczyk-Gajewska K. | - | IPPT PAN |
| | 35p. |
15. |
Frydrych K., Kowalczyk-Gajewska K., Grain refinement in the equal channel angular pressing process: simulations using the crystal plasticity finite element method,
MODELLING AND SIMULATION IN MATERIALS SCIENCE AND ENGINEERING, ISSN: 0965-0393, DOI: 10.1088/1361-651X/aad46d, Vol.26, No.6, pp.065015-1-32, 2018Streszczenie: Grain refinement due to severe plastic deformation is simulated using the crystal plasticity finite element method in the total Lagrangian setting. A rate-independent model with the regularized Schmid law is applied. As an example, a single pass of the equal channel angular pressing process is considered. Texture evolution, misorientation angle distributions and maps of new grains are presented. A special algorithm for tracking the creation of new grains in finite element simulations is developed. The results are analysed with respect to experimental data available in the literature. The possible mechanisms leading to the fragmentation of grains in a face centred cubic material are discussed. The influence of the quality of the microstructure representation on the simulation results is assessed Słowa kluczowe: crystal plasticity, severe plastic deformation, grain refinement, finite element method Afiliacje autorów:
Frydrych K. | - | IPPT PAN | Kowalczyk-Gajewska K. | - | IPPT PAN |
| | 35p. |
16. |
Mucha M.^{♦}, Wcisło B.^{♦}, Pamin J.^{♦}, Kowalczyk-Gajewska K., Instabilities in membrane tension: Parametric study for large strain thermoplasticity,
ARCHIVES OF CIVIL AND MECHANICAL ENGINEERING, ISSN: 1644-9665, DOI: 10.1016/j.acme.2018.01.008, Vol.18, No.4, pp.1055-1067, 2018Streszczenie: This paper deals with the numerical analysis of localized deformation for a rectangular plate in membrane tension, modelled with large strain thermoplasticity. The aim is to determine the influence of selected factors on the localization phenomena, which can result from geometrical, material, and thermal softening. Two types of boundary conditions are considered: plane stress and plane strain, as well as two yield functions, Huber–Mises–Hencky and Burzyński–Drucker–Prager, with selected values of friction angle. First, isothermal conditions are considered and next, a conductive case with thermal softening is studied. Moreover, three types of plastic behaviour are analysed: strain hardening (with different values of hardening modulus), ideal plasticity, and strain softening. Numerical tests, performed using AceGen/FEM packages, are carried out for the rectangular plate under tension with an imperfection, using three finite element discretizations. The results for plane strain in the isothermal model show that with the decrease of linear hardening modulus, we can observe stronger mesh sensitivity, while for plane stress, mesh sensitivity is visible for all cases. Furthermore, for the thermomechanical model the results also depend on the mesh density due to insufficient heat conduction regularization Słowa kluczowe: Thermoplasticity, Large strains, Strain localization, Parametric study Afiliacje autorów:
Mucha M. | - | Cracow University of Technology (PL) | Wcisło B. | - | Cracow University of Technology (PL) | Pamin J. | - | Cracow University of Technology (PL) | Kowalczyk-Gajewska K. | - | IPPT PAN |
| | 30p. |
17. |
Majewski M., Kursa M., Hołobut P., Kowalczyk-Gajewska K., Micromechanical and numerical analysis of packing and size effects in elastic particulate composites,
COMPOSITES PART B-ENGINEERING, ISSN: 1359-8368, DOI: 10.1016/j.compositesb.2017.05.004, Vol.124, pp.158-174, 2017Streszczenie: Effects of particle packing and size on the overall elastic properties of particulate random composites are analyzed. In order to account for the two effects the mean-field Morphologically Representative Pattern (MRP) approach is employed and an additional interphase surrounding inclusions (coating) is introduced. The analytical mean-field estimates are compared with the results of computational homogenization performed using the finite element (FE) method. Periodic unit cells with cubic crystal-type arrangements and representative volume elements with random distributions of particles are used for verification purposes. The validity of the MRP estimates with respect to the FE results is assessed. Słowa kluczowe: Composite materials, Elasticity, Micro-mechanics, Packing and size effects Afiliacje autorów:
Majewski M. | - | IPPT PAN | Kursa M. | - | IPPT PAN | Hołobut P. | - | IPPT PAN | Kowalczyk-Gajewska K. | - | IPPT PAN |
| | 45p. |
18. |
Sadowski P., Kowalczyk-Gajewska K., Stupkiewicz S., Consistent treatment and automation of the incremental Mori–Tanaka scheme for elasto-plastic composites,
COMPUTATIONAL MECHANICS, ISSN: 0178-7675, DOI: 10.1007/s00466-017-1418-z, Vol.60, pp.493-511, 2017Streszczenie: A consistent algorithmic treatment of the incremental Mori–Tanaka (MT) model for elasto-plastic composites is proposed. The aim is to develop a computationally efficient and robust micromechanical constitutive model suitable for large-scale finite-element computations. The resulting overall computational scheme is a doubly-nested iteration-subiteration scheme. The Newton method is used to solve the nonlinear equations at each level involved. Exact linearization is thus performed at each level so that a quadratic convergence rate can be achieved. To this end, the automatic differentiation (AD) technique is used, and the corresponding AD-based formulation is provided. Excellent overall performance of the present MT scheme in threedimensional finite-element computations is illustrated. Słowa kluczowe: Mori–Tanaka method, Composite materials, Elasto-plasticity, Finite element method, Automatic differentiation Afiliacje autorów:
Sadowski P. | - | IPPT PAN | Kowalczyk-Gajewska K. | - | IPPT PAN | Stupkiewicz S. | - | IPPT PAN |
| | 45p. |
19. |
Pieczyska E.A., Staszczak M., Kowalczyk-Gajewska K., Maj M., Golasiński K.M., Golba S.^{♦}, Tobushi H.^{♦}, Hayashi S.^{♦}, Experimental and numerical investigation of yielding phenomena in a shape memory polymer subjected to cyclic tension at various strain rates,
POLYMER TESTING, ISSN: 0142-9418, DOI: 10.1016/j.polymertesting.2017.04.014, Vol.60, pp.333-342, 2017Streszczenie: This paper presents experimental and numerical results of a polyurethane shape memory polymer (SMP) subjected to cyclic tensile loading. The goal was to investigate the polymer yielding phenomena based on the effects of thermomechanical coupling. Mechanical characteristics were obtained with a testing machine, whereas the SMP temperature accompanying its deformation process was simultaneously measured in a contactless manner with an infrared camera. The SMP glass transition temperature was approximately 45oC; therefore, when tested at room temperature, the polymer is rigid and behaves as solid material. The stress and related temperature changes at various strain rates showed how the SMP yield limit evolved in subsequent loading-unloading cycles under various strain rates. A two-phase model of the SMP was applied to describe its mechanical response in cyclic tension. The 3D Finite Element model of a tested specimen was used in simulations. Good agreement between the model predictions and experimental results was observed for the first tension cycle. Słowa kluczowe: Shape memory polymer, Tension cyclic loading, Thermomechanical coupling, Yield limit, Thermoelastic effect, Constitutive model Afiliacje autorów:
Pieczyska E.A. | - | IPPT PAN | Staszczak M. | - | IPPT PAN | Kowalczyk-Gajewska K. | - | IPPT PAN | Maj M. | - | IPPT PAN | Golasiński K.M. | - | IPPT PAN | Golba S. | - | University of Silesia (PL) | Tobushi H. | - | Aichi Institute of Technology (JP) | Hayashi S. | - | SMP Technologies Inc. (JP) |
| | 40p. |
20. |
Sadowski P., Kowalczyk-Gajewska K., Stupkiewicz S., Response discontinuities in the solution of the incremental Mori–Tanaka scheme for elasto-plastic composites,
ARCHIVES OF MECHANICS, ISSN: 0373-2029, Vol.69, No.1, pp.3-27, 2017Streszczenie: The incremental Mori–Tanaka model of elasto-plastic composites is discussed, and the corresponding finite-step formulation is shown to lead to discontinuities in the overall response at the instant of elastic-to-plastic transition in the matrix. Specifically, two situations may be encountered: the incremental equations may have two solutions or no solution. In the former situation, switching between the two solutions is associated with a jump in the overall stress. Response discontinuities are studied in detail for a special case of proportional deviatoric loading. The discontinuities constitute an undesirable feature of the incremental Mori–Tanaka scheme that apparently has not been discussed in the literature so far. Remedies to the related problems are briefly discussed. Słowa kluczowe: mean-field homogenization, Mori–Tanaka method, incremental scheme, composite materials, elasto-plasticity Afiliacje autorów:
Sadowski P. | - | IPPT PAN | Kowalczyk-Gajewska K. | - | IPPT PAN | Stupkiewicz S. | - | IPPT PAN |
| | 25p. |
21. |
Pamin J.^{♦}, Wcisło B.^{♦}, Kowalczyk-Gajewska K., Gradient-enhanced large strain thermoplasticity with automatic linearization and localization simulations,
JOURNAL OF MECHANICS OF MATERIALS AND STRUCTURES, ISSN: 1559-3959, DOI: 10.2140/jomms.2017.12.123, Vol.12, No.1, pp.123-146, 2017Streszczenie: The paper deals with the thermomechanical extension of a large strain hyperelasto-plasticity model and focuses on algorithmic aspects and localization simulations. The formulation includes the degradation of the yield strength due to the increase of an averaged plastic strain measure and temperature, thus, three sources for loss of stability are included in the description. A gradient-enhancement of the model is incorporated through an additional differential equation, but localization is also influenced by heat conduction. The finite element analysis is performed for an elongated plate in plane strain conditions, using different finite elements and values of material parameters related to regularization (internal length scales are related to gradient averaging as well as heat conduction). In particular, the influence of the F-bar enrichment on the simulation results is studied. All computational tests are performed using selfprogrammed user subroutines prepared within a symbolic-numerical tool AceGen which is equipped with automatic differentiation options, allowing for automatic linearization of the governing equations. Słowa kluczowe: thermoplasticity, softening, gradient averaging, strain localization, automatic linearization, AceGen package Afiliacje autorów:
Pamin J. | - | Cracow University of Technology (PL) | Wcisło B. | - | Cracow University of Technology (PL) | Kowalczyk-Gajewska K. | - | IPPT PAN |
| | 20p. |
22. |
Pieczyska E.A., Staszczak M., Maj M., Kowalczyk-Gajewska K., Golasiński K.M., Cristea M.^{♦}, Tobushi H.^{♦}, Hayashi S.^{♦}, Investigation of thermomechanical couplings, strain localization and shape memory properties in a shape memory polymer subjected to loading at various strain rates,
SMART MATERIALS AND STRUCTURES, ISSN: 0964-1726, DOI: 10.1088/0964-1726/25/8/085002, Vol.25, No.8, pp.085002-1-15, 2016Streszczenie: This paper presents experimental and modeling results of the effects of thermomechanical couplings occurring in a polyurethane shape memory polymer (SMP) subjected to tension at various strain rates within large strains. The SMP mechanical curves, recorded using a testing machine, and the related temperature changes, measured in a contactless manner using an IR camera, were used to investigate the polymer deformation process at various loading stages. The effects of thermomechanical couplings allowed the determination of the material yield point in the initial loading stage, the investigation of nucleation and development of the strain localization at larger strains and the estimation of the effects of thermoelastic behavior during the unloading process. The obtained stress–strain and thermal characteristics, the results of the dynamic mechanical analysis and estimated values of the shape fixity and shape recovery parameters confirmed that the shape memory polymer (T g = 45°C) is characterized by good mechanical and shape memory properties, as well as high sensitivity to the strain rate. The mechanical response of the SMP subjected to tension was simulated using the finite element method and applying the large strain, two-phase model. Strain localization observed in the experiment was well reproduced in simulations and the temperature spots were correlated with the accumulated viscoplastic deformation of the SMP glassy phase. Słowa kluczowe: shape memory polymer, thermomechanical coupling, infrared camera, tension test, strain rate, strain localization, constitutive model Afiliacje autorów:
Pieczyska E.A. | - | IPPT PAN | Staszczak M. | - | IPPT PAN | Maj M. | - | IPPT PAN | Kowalczyk-Gajewska K. | - | IPPT PAN | Golasiński K.M. | - | IPPT PAN | Cristea M. | - | Petru Poni Institute of Macromolecular Chemistry (RO) | Tobushi H. | - | Aichi Institute of Technology (JP) | Hayashi S. | - | SMP Technologies Inc. (JP) |
| | 40p. |
23. |
Frydrych K., Kowalczyk-Gajewska K., A three-scale crystal plasticity model accounting for grain refinement in fcc metals subjected to severe plastic deformations,
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING, ISSN: 0921-5093, DOI: 10.1016/j.msea.2016.01.101, Vol.658, pp.490-502, 2016Streszczenie: A new three-scale model of polycrystal accounting for grain refinement is proposed. The model is embedded into the crystal plasticity framework. With the experimental reference to the development of the dislocation induced cell substructure, a single crystallite in the representative grain aggregate is initially subdivided into subdomains with the crystallographic orientations slightly misoriented with respect to the nominal orientation of a parent grain. The predicted misorientation evolution of subgrains with respect to the reference orientation of a crystallite is an indicator of grain refinement. The correlation between the increase of a misorientation angle and a slip activity pattern is analyzed. The model predictions are compared with available experimental data. Słowa kluczowe: Crystal plasticity, Severe plastic deformation, Grain refinement Afiliacje autorów:
Frydrych K. | - | IPPT PAN | Kowalczyk-Gajewska K. | - | IPPT PAN |
| | 35p. |
24. |
Sadowski P., Kowalczyk-Gajewska K., Stupkiewicz S., Classical estimates of the effective thermoelastic properties of copper–graphene composites,
COMPOSITES PART B-ENGINEERING, ISSN: 1359-8368, DOI: 10.1016/j.compositesb.2015.06.007, Vol.80, pp.278-290, 2015Streszczenie: Significant research effort is concentrated worldwide on development of graphene-based metal-matrix composites with enhanced thermomechanical properties. In this work, we apply two classical micromechanical mean-field theories to estimate the effective thermoelastic properties that can be achieved in practice for a copper–graphene composite. In the modelling, graphene is treated as an anisotropic material, and the effect of its out-of-plane properties, which are less recognized than the in-plane properties, is studied in detail. To address the severe difficulties in processing of graphene-based metal-matrix composites, the copper–graphene composite is here assumed to additionally contain, due to imperfect processing, particles of graphite and voids. It is shown quantitatively that the related imperfections may significantly reduce the expected enhancement of the effective properties. The present predictions are also compared to the experimental data available in the literature. Słowa kluczowe: Metal-matrix composites (MMCs), Mechanical properties, Thermal properties, Micro-mechanics, Graphene Afiliacje autorów:
Sadowski P. | - | IPPT PAN | Kowalczyk-Gajewska K. | - | IPPT PAN | Stupkiewicz S. | - | IPPT PAN |
| | 40p. |
25. |
Czarnota C.^{♦}, Kowalczyk-Gajewska K., Salahouelhadj A.^{♦}, Martiny M.^{♦}, Mercier S.^{♦}, Modeling of the cyclic behavior of elastic–viscoplastic composites by the additive tangent Mori–Tanaka approach and validation by ﬁnite element calculations,
INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES, ISSN: 0020-7683, DOI: 10.1016/j.ijsolstr.2014.12.002, Vol.56-57, pp.96-117, 2015Streszczenie: This work deals with the prediction of the macroscopic behavior of two-phase composites, based on the Mori–Tanaka scheme combined with an additive/sequential interaction rule and tangent linearization of viscoplastic response. Cyclic tension compression loadings are considered to further validate the approach. The composite is made of spherical inclusions dispersed in a matrix. Both materials have an elastic–viscoplastic behavior. In a second part, finite element calculations are performed using ABAQUS/STANDARD software in order to validate the proposed homogenization technique. A representative volume element is analyzed with 30 randomly distributed inclusions. Comparisons between the additive tangent Mori–Tanaka scheme and finite element calculations are made for different volume fractions of inclusions, different contrasts in elastic and viscous properties and different strain rates and strain amplitudes. These comparisons demonstrate the efficiency of the proposed homogenization scheme. The effect of isotropization of the viscoplastic tangent stiffness is also investigated. It is concluded that quality of predictions does not benefit from such simplification, contrary to the known result for elastic–plastic case. Słowa kluczowe: Elasto-viscoplasticity, Homogenization, Finite element, Composite, Mori–Tanaka scheme Afiliacje autorów:
Czarnota C. | - | CNRS (FR) | Kowalczyk-Gajewska K. | - | IPPT PAN | Salahouelhadj A. | - | Lorraine University (FR) | Martiny M. | - | Lorraine University (FR) | Mercier S. | - | Clermont Université (FR) |
| | 40p. |
26. |
Pieczyska E.A., Maj M., Kowalczyk-Gajewska K., Staszczak M., Gradys A., Majewski M., Cristea M.^{♦}, Tobushi H.^{♦}, Hayashi S.^{♦}, Thermomechanical properties of polyurethane shape memory polymer–experiment and modelling,
SMART MATERIALS AND STRUCTURES, ISSN: 0964-1726, DOI: 10.1088/0964-1726/24/4/045043, Vol.24, pp.045043-1-16, 2015Streszczenie: In this paper extensive research on the polyurethane shape memory polymer (PU-SMP) is reported, including its structure analysis, our experimental investigation of its thermomechanical properties and its modelling. The influence of the effects of thermomechanical couplings on the SMP behaviour during tension at room temperature is studied using a fast and sensitive infrared camera. It is shown that the thermomechanical behaviour of the SMP significantly depends on the strain rate: at a higher strain rate higher stress and temperature values are obtained. This indicates that an increase of the strain rate leads to activation of different deformation mechanisms at the micro-scale, along with reorientation and alignment of the molecular chains. Furthermore, influence of temperature on the SMP's mechanical behaviour is studied. It is observed during the loading in a thermal chamber that at the temperature 20°C below the glass transition temperature (Tg) the PU-SMP strengthens about six times compared to the material above Tg but does not exhibit the shape recovery. A finite-strain constitutive model is formulated, where the SMP is described as a two-phase material composed of a hyperelastic rubbery phase and elastic-viscoplastic glassy phase. The volume content of phases is governed by the current temperature. Finally, model predictions are compared with the experimental results. Słowa kluczowe: shape memory polyurethane, thermomechanical couplings, infrared camera, temperature change, dynamic mechanical analysis, strain rate, constitutive model Afiliacje autorów:
Pieczyska E.A. | - | IPPT PAN | Maj M. | - | IPPT PAN | Kowalczyk-Gajewska K. | - | IPPT PAN | Staszczak M. | - | IPPT PAN | Gradys A. | - | IPPT PAN | Majewski M. | - | IPPT PAN | Cristea M. | - | Petru Poni Institute of Macromolecular Chemistry (RO) | Tobushi H. | - | Aichi Institute of Technology (JP) | Hayashi S. | - | SMP Technologies Inc. (JP) |
| | 40p. |
27. |
Kowalczyk-Gajewska K., Sztwiertnia K.^{♦}, Kawałko J.^{♦}, Wierzbanowski K.^{♦}, Wroński M.^{♦}, Frydrych K., Stupkiewicz S., Petryk H., Texture evolution in titanium on complex deformation paths: Experiment and modelling,
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING, ISSN: 0921-5093, DOI: 10.1016/j.msea.2015.04.040, Vol.637, pp.251-263, 2015Streszczenie: Texture evolution in commercially pure titanium deformed by equal-channel angular pressing (ECAP) and extrusion with forward–backward rotating die (KoBo) is studied both experimentally and numerically. New results are provided that demonstrate the effects of distinct and complex deformation paths on the texture in the ultra-fine grained (UFG) material obtained after severe plastic deformation (SPD). The numerical simulations are based on the self-consistent viscoplastic method of grain-to-polycrystal scale transition. A recently proposed modification of the probabilistic scheme for twinning is used that provides consistent values of the twin volume fraction in grains. The basic components of the experimentally observed texture are reasonably well reproduced in the modelling. The numerical simulations provide an insight into the internal mechanisms of plastic deformation, revealing substantial activity of mechanical twinning in addition to the basal and prismatic slip in titanium processed by ECAP. Słowa kluczowe: Texture evolution, UFG materials, SPD processes, Crystal plasticity, Twinning Afiliacje autorów:
Kowalczyk-Gajewska K. | - | IPPT PAN | Sztwiertnia K. | - | inna afiliacja | Kawałko J. | - | inna afiliacja | Wierzbanowski K. | - | inna afiliacja | Wroński M. | - | inna afiliacja | Frydrych K. | - | IPPT PAN | Stupkiewicz S. | - | IPPT PAN | Petryk H. | - | IPPT PAN |
| | 35p. |
28. |
Kursa M., Kowalczyk-Gajewska K., Petryk H., Multi-objective optimization of thermo-mechanical properties of metal-ceramic composites,
COMPOSITES PART B-ENGINEERING, ISSN: 1359-8368, DOI: 10.1016/j.compositesb.2014.01.009, Vol.60, pp.586-596, 2014Streszczenie: The optimization procedure is worked out for finding an optimal content of phases in metal–ceramic composites in case of conflicting objectives regarding thermo-mechanical properties of the material for a specific target application. Relationships between the material composition and effective properties of the composite are calculated by employing several methods of continuum micromechanics. A constrained minimization problem is solved for a single objective function based on the weighted squared distances from the best available thermo-mechanical properties for the material system selected. A compound block diagram is proposed for quick assessment of the consequences of deviating from the optimal composition. The developed procedure is applied to practical examples of Al2O3–Cu composites for brake disks and Al2O3–NiAl composites for valves of potential use in automotive industry. Słowa kluczowe: Metal–matrix composites (MMCs), Thermomechanical, Plastic deformation, Micro-mechanics, Multi-criteria optimization Afiliacje autorów:
Kursa M. | - | IPPT PAN | Kowalczyk-Gajewska K. | - | IPPT PAN | Petryk H. | - | IPPT PAN |
| | 40p. |
29. |
Pieczyska E.A., Maj M., Kowalczyk-Gajewska K., Staszczak M., Urbański L., Tobushi H.^{♦}, Hayashi S.^{♦}, Cristea M.^{♦}, Mechanical and Infrared Thermography Analysis of Shape Memory Polyurethane,
Journal of Materials Engineering and Performance, ISSN: 1059-9495, DOI: 10.1007/s11665-014-0963-2, Vol.23, No.7, pp.2553-2560, 2014Streszczenie: Multifunctional new material—polyurethane shape memory polymer (PU-SMP)—was subjected to tension carried out at room temperature at various strain rates. The influence of effects of thermomechanical couplings on the SMP mechanical properties was studied, based on the sample temperature changes, measured by a fast and sensitive infrared camera. It was found that the polymer deformation process strongly depends on the strain rate applied. The initial reversible strain is accompanied by a small drop in temperature, called thermoelastic effect. Its maximal value is related to the SMP yield point and increases upon increase of the strain rate. At higher strains, the stress and temperature significantly increase, caused by reorientation of the polymer molecular chains, followed by the stress drop and its subsequent increase accompanying the sample rupture. The higher strain rate, the higher stress, and temperature changes were obtained, since the deformation process was more dynamic and has occurred in almost adiabatic conditions. The constitutive model of SMP valid in finite strain regime was developed. In the proposed approach, SMP is described as a two-phase material composed of hyperelastic rubbery phase and elastic-viscoplastic glassy phase, while the volume content of phases is specified by the current temperature. Słowa kluczowe: constitutive model, dynamic mechanical analysis, shape memory polyurethane, strain rate, temperature change, thermomechanical couplings Afiliacje autorów:
Pieczyska E.A. | - | IPPT PAN | Maj M. | - | IPPT PAN | Kowalczyk-Gajewska K. | - | IPPT PAN | Staszczak M. | - | IPPT PAN | Urbański L. | - | IPPT PAN | Tobushi H. | - | Aichi Institute of Technology (JP) | Hayashi S. | - | SMP Technologies Inc. (JP) | Cristea M. | - | Petru Poni Institute of Macromolecular Chemistry (RO) |
| | 20p. |
30. |
Pieczyska E.A., Kowalczyk-Gajewska K., Maj M., Staszczak M., Tobushi H.^{♦}, Thermomechanical investigation of TiNi shape memory alloy and PU shape memory polymer subjected to cyclic loading,
Procedia Engineering, ISSN: 1877-7058, DOI: 10.1016/j.proeng.2014.06.264, Vol.74, pp.287-292, 2014Streszczenie: In applications to sensors, actuators, guide wires, special grips for handicapped people, a shape memory alloy (SMA) or shape memory polymer (SMP) are used as working elements that perform cyclic motions. In order to evaluate the reliability of the shape memory materials (SMM), cycling and fatigue deformation properties are investigated. Since the SMM are very sensitive to temperature, not only mechanical properties but also their related temperature changes accompanying the deformation process should be taken into account. The presented paper embraces experimental investigation of effects of thermomechanical couplings occurring in shape memory alloy and shape memory polymer subjected to various kinds of cycling loading. The deformation was carried out on MTS 858 Testing machine. The strain was measured by a mechanical extensometer, so the stress-strain characteristics were elaborated with high accuracy. Furthermore, a fast and sensitive FLIR Co Phoenix infrared (IR) measurement system was used in order to record infrared radiation from the sample surface. It enables obtaining temperature distribution of the sample as a function of the deformation parameters. For each strain cycle, an increase in temperature during the loading and the temperature decrease during the unloading processes was observed. It was found that the temperature increment recorded during the cyclic deformation depends on the strain rate, the kind of the material and the test conditions. The higher the strain rate the higher the stress and temperature changes were obtained, since the deformation process was more dynamic and has occurred in almost adiabatic conditions. It was shown that various deformation mechanisms are active during various loading stages. Słowa kluczowe: shape memory alloy, shape memory polymer, cyclic deformation, thermomechanical coupling, infrared camera Afiliacje autorów:
Pieczyska E.A. | - | IPPT PAN | Kowalczyk-Gajewska K. | - | IPPT PAN | Maj M. | - | IPPT PAN | Staszczak M. | - | IPPT PAN | Tobushi H. | - | Aichi Institute of Technology (JP) |
| |
31. |
Wcisło B.^{♦}, Pamin J.^{♦}, Kowalczyk-Gajewska K., Gradient-enhanced damage model for large deformations of elastic-plastic materials,
ARCHIVES OF MECHANICS, ISSN: 0373-2029, Vol.65, No.5, pp.407-428, 2013Streszczenie: This paper deals with the development of a family of gradient-enhanced elasticity-damage-plasticity models for the simulation of failure in metallic and composite materials. The model incorporates finite deformations and is developed with the assumption of isotropy and isothermal conditions. The gradient enhancement applied to the damage part of the model aims at removing pathological sensitivity to the finite element discretization which can occur due to material softening.
The attention is focused on the algorithmic aspects and on the implementation of the model using AceGen tool. The numerical verification tests of the described model are performed using the Mathematica-based package AceFEM. Particularly, uniaxial tension test for a bar with a variable cross-section and tension of a perforated plate are examined. Słowa kluczowe: arge strains, damage, plasticity, gradient-enhancement, AceGen package Afiliacje autorów:
Wcisło B. | - | Cracow University of Technology (PL) | Pamin J. | - | Cracow University of Technology (PL) | Kowalczyk-Gajewska K. | - | IPPT PAN |
| | 20p. |
32. |
Kowalczyk-Gajewska K., Stupkiewicz S., Modelling of Texture Evolution in Kobo Extrusion Process,
ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, DOI: 10.2478/v10172-012-0160-y, Vol.58, No.1, pp.113-118, 2013Streszczenie: The paper is aimed at modelling of evolution of crystallographic texture in KOBO extrusion which is an unconventional process of extrusion assisted by cyclic torsion. The analysis comprises two steps. In the first step, the kinematics of the KOBO extrusion process is determined using the finite element method. A simplifying assumption is adopted that the material flow is not significantly affected by plastic hardening, and thus a rigid-viscoplastic material model with no hardening is used. In the second step, evolution of crystallographic texture is modelled along the trajectories obtained in the first step. A micromechanical model of texture evolution is used that combines the crystal plasticity model with a self-consistent grain-to-polycrystal scale transition scheme, and the VPSC code is used for that purpose. Since each trajectory corresponds to a different deformation path, the resulting pole figures depend on the position along the radius of the extruded rod. Słowa kluczowe: plasticity, microstructure, crystallographic texture, KOBO extrusion Afiliacje autorów:
Kowalczyk-Gajewska K. | - | IPPT PAN | Stupkiewicz S. | - | IPPT PAN |
| | 20p. |
33. |
Kowalczyk-Gajewska K., Crystal plasticity models accounting for twinning,
COMPUTER METHODS IN MATERIALS SCIENCE / INFORMATYKA W TECHNOLOGII MATERIAŁÓW, ISSN: 1641-8581, Vol.13, No.4, pp.436-451, 2013Streszczenie: Different approaches to account for twinning in crystal plasticity models are discussed. In particular, three main issues related to this mechanism of plastic deformation are addressed: modelling of texture evolution in the presence of twinning, impact of slip-twin interactions on hardening laws formulation and influence of layered substructure on the macroscopic response of materials. Some of the discussed modelling tools are illustrated with an example of titanium aluminide Słowa kluczowe: crystal plasticity, twinning, texture evolution, hardening Afiliacje autorów:
Kowalczyk-Gajewska K. | - | IPPT PAN |
| | 10p. |
34. |
Kowalczyk-Gajewska K., Estimation of overall properties of random polycrystals with the use of invariant decompositions of Hooke’s tensor,
INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES, ISSN: 0020-7683, DOI: 10.1016/j.ijsolstr.2012.06.002, Vol.49, No.21, pp.3022-3037, 2012Streszczenie: In the paper the theoretical analysis of bounds and self-consistent estimates of overall properties of linear random polycrystals composed of arbitrarily anisotropic grains is presented. In the study two invariant decompositions of Hooke’s tensors are used. The applied method enables derivation of novel expressions for estimates of the bulk and shear moduli, which depend on invariants of local stiffness tensor. With use of these expressions the materials are considered for which at the local level constraints are imposed on deformation or some stresses are unsustained Słowa kluczowe: Creep, Anisotropic material, Polycrystalline material, Invariant decompositions Afiliacje autorów:
Kowalczyk-Gajewska K. | - | IPPT PAN |
| | 40p. |
35. |
Kowalczyk-Gajewska K., Petryk H., Sequential linearization method for viscous/elastic heterogeneous materials,
EUROPEAN JOURNAL OF MECHANICS A-SOLIDS, ISSN: 0997-7538, Vol.30, No.5, pp.650-664, 2011Streszczenie: The paper addresses the problem of suitable approximation of the interaction between phases in heterogeneous materials that exhibit both viscous and elastic properties. A novel approach is proposed in which linearized subproblems for an inhomogeneity-matrix system with viscous or elastic interaction rules are solved sequentially within one incremental step. It is demonstrated that in the case of a self-consistent averaging scheme, an additional accommodation subproblem, besides purely viscous and elastic subproblems, is to be solved in order to estimate the material response satisfactorily. By examples of an isotropic two-phase material it is shown that the proposed approach provides acceptable predictions in comparison with the existing models. Słowa kluczowe: Micromechanics, Viscoelasticity, Viscoplasticity, Homogenization, Self-consistent scheme Afiliacje autorów:
Kowalczyk-Gajewska K. | - | IPPT PAN | Petryk H. | - | IPPT PAN |
| | 30p. |
36. |
Kowalczyk-Gajewska K., Micromechanical model of polycrystalline materials with lamellar substructure,
ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, Vol.56, No.2, pp.509-522, 2011Streszczenie: Micromechanical model of polycrystalline materials with lamellar substructure is presented. The lamellar microstructure of grains is accounted for using the well-established framework developed for layered composites. Within the approach different scale transition rules between the level of lamellar grain and the polycrystalline sample can be employed. The model capabilities are tested using the example of TiAl intermetallic. Elastic properties and the initial yield surface for the lamellar grain (PST crystal) and for the untextured polycrystal are estimated. Elastic and plastic anisotropy degree is analyzed Słowa kluczowe: micromechanics, homogenization, lamellar substructure, anisotropic material, anisotropy degree Afiliacje autorów:
Kowalczyk-Gajewska K. | - | IPPT PAN |
| | 20p. |
37. |
Kowalczyk-Gajewska K., Modelling of texture evolution in metals accounting for lattice reorientation due to twinning,
EUROPEAN JOURNAL OF MECHANICS A-SOLIDS, ISSN: 0997-7538, Vol.29, No.1, pp.28-41, 2010Streszczenie: Twinning has been incorporated into a crystal plasticity model with the regularized Schmid law. In order to account for the appearance of twin-related orientations, a new probabilistic twin reorientation scheme that maintains the number of reoriented grains consistent with the accumulated deformation by twinning within the polycrystalline element, has been developed. A hardening rule describing slip–twin interactions has been also proposed. Model predictions concerning material response and texture evolution have been analyzed for fcc materials of low stacking fault energy. Słowa kluczowe: Crystal plasticity, Twinning, Hardening, Texture, Anisotropic material, Polycrystal model Afiliacje autorów:
Kowalczyk-Gajewska K. | - | IPPT PAN |
| | 32p. |
38. |
Kowalczyk-Gajewska K., Bounds and self-consistent estimates of overall properties for random polycrystals described by linear constitutive laws,
ARCHIVES OF MECHANICS, ISSN: 0373-2029, Vol.61, No.6, pp.475-503, 2009Streszczenie: Analytical solutions for bounds of overall properties are derived for single-phase polycrystalline materials of random texture, composed of grains with arbitrary anisotropy and described by the linear constitutive law. Self-consistent estimates are found for these materials and they are studied in more details when anisotropic grains are volumetrically isotropic. Reduction of the above solutions for incompressible materials or materials with constraint modes of deformation is also derived. Existence and uniqueness of the obtained solutions are discussed. In order to obtain the solutions, simultaneously the spectral and harmonic decomposition of fourth order Hooke’s tensor are used. Utility of the obtained results is demonstrated on the examples of metals and alloys of high specific strength and stiffness Słowa kluczowe: anisotropic materials, self-consistent estimates, polycrystals Afiliacje autorów:
Kowalczyk-Gajewska K. | - | IPPT PAN |
| | 27p. |
39. |
Kowalczyk-Gajewska K., Pęcherski R.B., Phenomenological description of the effect of micro-shear banding in micromechanical modelling of polycrystal plasticity,
ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, Vol.54, pp.717-730, 2009Streszczenie: The rigid-plastic crystal plasticity model accounting for the effect of micro-shear banding mechanism on the reduction of the global strain hardening rate is presented. The instantaneous contribution of micro-shear bands in the rate of plastic deformation is described by means of the constitutive function that depends on the type of strain path specified by the current direction of strain rate tensor. The capabilities of the model are explored by studying the strain-stress behavior of polycrystalline material together with the crystallographic texture evolution in the polycrystalline element Słowa kluczowe: Crystallographic texture, Anisotropic material, Crystal plasticity, Polycrystalline material, Micro-shear banding Afiliacje autorów:
Kowalczyk-Gajewska K. | - | IPPT PAN | Pęcherski R.B. | - | IPPT PAN |
| | 20p. |
40. |
Kowalczyk-Gajewska K., Ostrowska-Maciejewska J.^{♦}, Review on spectral decomposition of Hooke's tensor for all symmetry groups of linear elastic materials,
ENGINEERING TRANSACTIONS (ROZPRAWY INŻYNIERSKIE), ISSN: 0867-888X, Vol.57, pp.145-183, 2009Streszczenie: The spectral decomposition of elasticity tensor for all symmetry groups of a linearly elastic material is reviewed. In the paper it has been derived in non-standard way by imposing the symmetry conditions upon the orthogonal projectors instead of the stiffness tensor itself. The numbers of independent Kelvin moduli and stiffness distributors are provided. The corresponding representation of the elasticity tensor is specified Słowa kluczowe: linear elasticity, anisotropy, symmetry group, spectral decomposition Afiliacje autorów:
Kowalczyk-Gajewska K. | - | IPPT PAN | Ostrowska-Maciejewska J. | - | inna afiliacja |
| | 6p. |
41. |
Żebro T.^{♦}, Kowalczyk-Gajewska K., Pamin J.^{♦}, A geometrically nonlinear model of scalar damage coupled to plasticity,
Czasopismo Techniczne. Mechanika, ISSN: 0011-4561, Vol.20, No.105, pp.251-262, 2008 | |
42. |
Kowalczyk-Gajewska K., Pamin J.^{♦}, Żebro T.^{♦}, Development of gradient-enhanced damage-plasticity formulations for large deformations,
Czasopismo Techniczne. Mechanika, ISSN: 0011-4561, Vol.20, No.105, pp.47-58, 2008 | |
43. |
Gambin W., Kowalczyk-Gajewska K., Kudrjavceva L.T.^{♦}, Micunovic M.V.^{♦}, Two-scale approach to dynamic localization failure of AISI 316H stainless steel sheets,
Theoretical and Applied Mechanics, ISSN: 1450-5584, DOI: 10.2298/TAM0803093G, Vol.35, No.1-3, pp.93-104, 2008Streszczenie: Dynamic localization failure of a thin sheet made of AISI 316H steel is considered on the macroscopic and mesoscopic level for proportional and nonproportional stress paths. On the macroscopic level, we propose: (1) the replacement of time as independent variable by a function of plastic dissipation and (2) dependence of the initial equivalent yield stress on stress rate. On the mesoscopic level - the regularized Schmid model for description of the single grain behavior is used and the polycrystalline yield surface generated by the texture development enables to improve the Forming Limit Diagrams for the sheet element. Słowa kluczowe: dynamic localization failure, Forming Limit Diagrams, regularized Schmid law, sheet textures Afiliacje autorów:
Gambin W. | - | IPPT PAN | Kowalczyk-Gajewska K. | - | IPPT PAN | Kudrjavceva L.T. | - | inna afiliacja | Micunovic M.V. | - | inna afiliacja |
| |
44. |
Kowalczyk-Gajewska K., Mróz Z., Pęcherski R.B., Micromechanical modelling of polycrystalline materials under non-proportional deformation paths,
ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, Vol.52, pp.181-192, 2007Streszczenie: The rigid-plastic crystal plasticity model with single yield surface of 2n-degree is applied to simulate the polycrystalline behaviour and the crystallographic texture development under non-proportional deformation paths. The role of two controlling parameters: the amplitude and frequency for the processes of tension or compression assisted by cyclic torsion of thin-walled tubes made of copper is analysed. The effect of micro-shear bands on the reduction of global hardening rate is described by means of the contribution function of shear banding in the rate of plastic deformation. The conclusions drawn from the study can find also application in the extension of the analysis for high strength and hard deformable materials. Słowa kluczowe: micromechanics, modelling of materials, rigid-plastic solids, crystal plasticity, texture, cyclic torsion, non-proportional deformation path, micro-shear bands Afiliacje autorów:
Kowalczyk-Gajewska K. | - | IPPT PAN | Mróz Z. | - | IPPT PAN | Pęcherski R.B. | - | IPPT PAN |
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45. |
Mróz Z., Kowalczyk-Gajewska K., Maciejewski J., Pęcherski R.B., Tensile or compressive plastic deformation of cylinders assisted by cyclic torsion,
ARCHIVES OF MECHANICS, ISSN: 0373-2029, Vol.58, No.6, pp.497-527, 2006Streszczenie: Technological metal forming processes of extrusion, forging and rolling with imposed cyclic torsion or shear deformation have been recently studied in view of their advantages with respect to monotonic loading processes, cf. Bochniak and Korbel [2–4]. The present work is aimed to analyze such process in the case of simple tension or compression of a cylindrical tube with imposed cyclic torsional deformation. The material element response is assumed to be rigid-perfectly plastic or elastic-perfectly plastic. For these models, the analytical solutions can be provided for the steady cyclic responses and the effect of two process parameters, namely the ratio of shear and axial strain rates η and the amplitude of shear strain γm, can be clearly demonstrated. Three different regimes of cyclic response can be visualized in the plane η, γm. The cyclic response of a cylinder under combined axial compression and cyclic torsion is predicted by considering a simplified model of a set of concentric tubes and neglecting their radial stress interaction. The axial force and torsional moment are then specified by averaging the responses of consecutive tubes. The cyclic response diagrams for the cylinder are then generated in terms of axial force and torsional moment related to axial deformation and angle of twist Słowa kluczowe: cyclic torsion, plastic deformation of cylinders, elastic-perfectly plastic model, rigid-perfectly plastic model, analytical solutions of cyclic response of a cylinder Afiliacje autorów:
Mróz Z. | - | IPPT PAN | Kowalczyk-Gajewska K. | - | IPPT PAN | Maciejewski J. | - | IPPT PAN | Pęcherski R.B. | - | IPPT PAN |
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46. |
Kowalczyk-Gajewska K., Ostrowska-Maciejewska J.^{♦}, Energy-based limit criteria for anisotropic elastic materials with constraints,
ARCHIVES OF MECHANICS, ISSN: 0373-2029, Vol.57, No.2-3, pp.133-155, 2005 | |
47. |
Kowalczyk-Gajewska K., Gambin W., Pęcherski R.B., Ostrowska-Maciejewska J.^{♦}, Modelling of crystallographic texture development in metals accounting for micro-shearbands,
ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, Vol.50, No.3, pp.575-593, 2005Streszczenie: The rigid-plastic model for the single grain is developed in which the velocity gradient is split into two parts connected with crystallographic slip and micro-shear bands respectively. For crystallographic slip the regularized Schmid law proposed by Gambin is used. For the micro-shear bands the model developed by Pęcherski, which accounts for the contribution of this mechanism in the rate of plastic deformation by means of a function fms is applied. Different constitutive equations for the plastic spin due to two considered mechanisms of plastic deformation are used. The present model is applied to simulate crystallographic texture evolution in the polycrystalline element. Słowa kluczowe: crystallographic texture, modelling of texture, micro-shear bands, regularized Schnid law, plastic spin Afiliacje autorów:
Kowalczyk-Gajewska K. | - | IPPT PAN | Gambin W. | - | IPPT PAN | Pęcherski R.B. | - | IPPT PAN | Ostrowska-Maciejewska J. | - | inna afiliacja |
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48. |
Kowalczyk K., Gambin W., Model of plastic anisotropy evolution with texture-dependent yield surface,
International Journal of Plasticity, ISSN: 0749-6419, DOI: 10.1016/S0749-6419(03)00010-X, Vol.20, No.1, pp.19-54, 2004Streszczenie: Model of evolution of plastic anisotropy due to crystallographic texture development, in metals subjected to large deformation processes, is presented. The model of single grain with the regularized Schmid law proposed by Gambin is used. Evolution of crystallographic texture during drawing, rolling and pure shear is calculated. Phenomenological texture-dependent yield surface for polycrystalline sheets is proposed. Evolution of this yield surface is compared with evolution of phenomenological higher order yield surfaces proposed by Hill and Barlat with Lian for drawing, rolling and pure shear processes. The change of the Hill yield surface and the Barlat–Lian yield surface is obtained by replacing material parameters present in these conditions by texture-dependent functions. Słowa kluczowe: Crystallographic texture, Anisotropic material, Crystal plasticity, Polycrystalline material Afiliacje autorów:
Kowalczyk K. | - | IPPT PAN | Gambin W. | - | IPPT PAN |
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49. |
Kowalczyk K., Mróz Z., Description of anisotropy of textured metals using macro and micro models,
JOURNAL DE PHYSIQUE IV, ISSN: 1155-4339, DOI: 10.1051/jp4:20030188, Vol.105, pp.199-206, 2003Streszczenie: In the paper description of anisotropy of textured metals using macro and micro models is compared. In the present macro-approach the texture anisotropy is described by introducing a second order microstructure tensor whose principal directions specify the orthotropy axes. A scalar orientation parameter $\eta$ is introduced in order to specify the relative orientation of the generalized traction vector with respect to anisotropy axes. The yield stress is assumed to depend on the parameter $\eta$ with specific forms introduced in order to provide quantitative description of yield stress variation with loading orientation. The phenomenological approach is next confronted with the microstructural approach based on the analysis of crystallographic slip and induced lattice reorientation in a representative grain aggregate. The resulting yield surface for polycrystalline aggregate is then compared with the macroscopic description based on the orientational variation of the yield stress. The proposed macro description seems much simpler from micro-approach and could prove convenient in the analysis of technological processes for textured materials. Afiliacje autorów:
Kowalczyk K. | - | IPPT PAN | Mróz Z. | - | IPPT PAN |
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